Page 319 - Canadian BC Science 9

Checking Concepts
1. What is the name of the property of a material that slows down current and converts electrical energy into other forms of energy?
2. Using Ohm’s law, state the relationship of current, resistance, and voltage.
3. What two values do you need in order to calculate resistance?
4. (a) What is the unit of resistance? (b) What is its symbol?
5. What is used to control current and potential difference in a circuit?
6. Explain how manufacturers indicate the value of resistance on each resistor.
7. Draw the symbol used to represent a resistor in a circuit diagram.
Understanding Key Ideas
8. A 1.2 A current flows through a 250 􏰀 resistor. Calculate the voltage across this resistor.
9. A 120 􏰀 resistor is connected to a 12 V battery. Calculate the current through the resistor.
10. An unknown resistor transforms 2.0 mA of current when connected to a 9.0 V battery. Calculate the value of this resistor.
11. A classmate hands you a resistor that has the following colour bands: yellow, orange, red, and silver. What is the resistance of this resistor?
12. A light bulb is connected to a battery and the brightness of the light is observed. A resistor is then connected between the battery and the light bulb and the brightness of the light decreases. Explain this observation using what you know about energy and circuit components.
13. Draw a circuit diagram for the following circuit.
Pause and Reflect
Suppose you are given several batteries, an ammeter, voltmeter, connecting wires, and a resistor that has no coloured bands indicating its value. How could you determine an accurate value for this resistor?
Chapter 8 Ohm’s law describes the relationship of current, voltage, and resistance. • MHR 301